The field of the invention is expandable styrene polymer particles for the preparation of molded articles. The present invention is particularly concerned with coating the particulate, expandable styrene polymers with organosols containing quaternary ammonium salts and using the coated expandable styrene polymers in making molded articles.
Expandable styrene polymers, like most plastics, are an insulator with low surface conductivity. As a result, they pick up and hold static electricity for extended periods of time. An effective antistatic treatment for expandable styrene polymers must provide a webb of ionic and/or hydrophilic pathways through which a charge can be dissipated. These pathways are most effective as a network throughout the molded part rather than as a molded part surface coating, as in the dipping procedure. Antistatic agents do not readily adhere to the expandable bead surface in most coating procedures and are easily removed from the beads during the expansion and molding processes. Due to the sensitive nature of suspension stability in polymerization and impregnation, antistat addition during these steps is not practical.
U.S. Pat. No. 4,495,224 teaches to prepare expandable styrene polymers having improved molding characteristics by coating the polymer particles with glycerin esters of long chain fatty acids. The coating is made by forming organosols with pulverulent glycerin esters in aliphatic hydrocarbons.